package com.liang.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//操作数据库的公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    static {
//        通过类加载器读取对应的资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        Properties properties = new Properties();
        try {
            properties.load(is);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");


    }

    //        获取数据库连接
    public static Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return connection;
    }

    //    编写查询公共类
    public static ResultSet execute(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet, String sql, Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
//            prepareStatement占位符从1开始
            preparedStatement.setObject(i + 1, params[i]);
        }
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }

    //    增删改公共方法
    public static Boolean execute(Connection connection, PreparedStatement preparedStatement, String sql, Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
//            prepareStatement占位符从1开始
            preparedStatement.setObject(i + 1, params[i]);
        }
        int updateRows = preparedStatement.executeUpdate();
        return updateRows > 0;
    }

    //    关闭连接
    public static boolean closeResource(ResultSet resultSet, PreparedStatement pr, Connection con) {
        boolean flag = true;
        if (resultSet != null) {
            try {
                resultSet.close();
                resultSet = null;
            } catch (SQLException e) {
                flag = false;
                e.printStackTrace();
            }
        }
        if (pr != null) {
            try {
                pr.close();
                pr = null;
            } catch (SQLException e) {
                flag = false;
                e.printStackTrace();
            }
        }
        if (con != null) {
            try {
                con.close();
                con = null;
            } catch (SQLException e) {
                flag = false;
                e.printStackTrace();
            }
        }
        return flag;
    }
}
